When an ophthalmologist examines a patient, an auto refractometer is used to determine the nature of the patient's ametropia (defective vision). The auto refractometer is generally connected to the ophthalmologist's personal computer, which computer includes software capable of processing the data from the refractometer and serving in particular to display the measurements taken by the auto refractometer. An example of software that is in widespread use for this purpose is the StudioVision software available from the supplier RealVision.
Typically, the various kinds of ametropia are as follows: myopia, hyperopia, astigmatism, and presbyopia.
The measurements performed by the auto refractometer are objective measurements. For each eye of the patient, they provide in particular the following conventional data as determined by the above-mentioned software:                sphere (depending on its sign, this measurement relates to the degree of myopia or of hyperopia of the eye in question of the patient;        cylinder (a measurement relating to the degree of astigmatism;        axis (a measurement relating to the axis of astigmatism);        addition (a measurement relating to the presbyopia correction for progressive lenses; specifying values to be added to far vision in order to provide a correction for near vision);        radius (radii) (measured relative to the radius of curvature of the cornea of the patient's eye. In general, two radii of curvature of the cornea are measured in order to determine the maximum keratometry and the minimum keratometry), and in general, the following additional data:                    the axis of the or each radius of curvature of the cornea involved in the measurement.                        
On the basis of these objective measurements, the ophthalmologist generally carries out subjective evaluation seeking to adapt the objective data supplied by the auto refractometer. This adaptation seeks to take account of the daily lifestyle of the patient, such as daily exposure to light, nature of the patient's work, or the sporting activity of the patient.
Thereafter, the ophthalmologist determines the characteristics of the contact lenses that are to be proposed to the patient.
For this purpose, the ophthalmologist takes account of the nature of the patient's ametropia, as determined by the auto refractometer, in order to select the shape of the lens (e.g. spherical, toric, multifocal), that is best suited to the patient.
The ophthalmologist also takes account of the nature of the material from which the contact lens is made (e.g. silicone hydrogel, hydrogel, rigid).
Finally, the ophthalmologist takes account of the frequency with which the lens is to be worn that the ophthalmologist considers as being the best suited to the patient (e.g. lenses on a daily, monthly, bimonthly, or quarterly basis).
The ophthalmologist also takes account of the measurements performed by the auto refractometer, and possibly of any subjective correction to those measurements.
It should be observed that when a subjective evaluation is made on the basis of objective measurements taken by the auto refractometer (as is often the case), the ophthalmologist must personally make corrections to the measurements that have been taken by the auto refractometer.
The ophthalmologist relies on personal experience and/or on equivalence tables that are well known to the person skilled in the art.
For certain contact lenses, this correction is quite easy to do and the ophthalmologist makes a selection based on personal experience.
Nevertheless, this is not true of all contact lenses. For example, the correction is difficult to determine when toric lenses need to be proposed for a patient. Under such circumstances, the ophthalmologist requires a certain amount of time to select the correction that is finally chosen, relying on equivalence tables.
This can lead to a loss of time, and possibly also to error in the subjective correction.
Once all of the characteristics of the contact lenses have been determined, the ophthalmologist takes the lenses in question from a stock. For this purpose, the ophthalmologist generally has a plurality of storage cabinets from various suppliers.
After a certain amount of time, the ophthalmologist must then reorder contact lenses that are no longer available in the ophthalmologist's own stock so that an employee of the supplier can replenish the stock (restocking).
This leads to a loss of time for the ophthalmologist. Furthermore, it is possible for that to lead to errors in the kinds of contact lenses that are to be supplied.
If the ophthalmologist does not make an order, regular visits by the supplier can also serve to achieve restocking, however that is generally not sufficient since the supplier has no idea about which contact lenses are missing.
Restocking contact lenses available on the premises of an ophthalmologist (test lenses) thus leads to difficulties, both for the ophthalmologist and for the ophthalmologist's supplier.